Ascorbic acid specific utilization by some yeasts.

Area of Science:

• Microbiology
• Yeast Physiology
• Biochemistry

Background:

• Ascorbic acid (vitamin C) and its isomer, iso-ascorbic acid, are important compounds with various biological roles.
• The metabolic pathways and nutritional requirements of many yeast species are not fully understood.
• Investigating yeast's ability to metabolize different carbon sources can reveal novel biochemical capabilities.

Purpose of the Study:

• To screen a diverse collection of yeast strains for their ability to utilize ascorbic acid and iso-ascorbic acid as sole carbon sources.
• To identify specific yeast species capable of metabolizing these compounds.
• To understand the variability in metabolic capabilities within and between yeast genera.

Main Methods:

• Screening of 180 yeast strains from 17 genera and 53 species.
• Culturing yeasts on media where ascorbic acid or iso-ascorbic acid was the sole available carbon source.
• Observing and recording yeast growth to determine utilization capability.

Main Results:

• 157 out of 180 tested yeast strains could not grow on either ascorbic acid or iso-ascorbic acid.
• Growth was observed for strains from seven Cryptococcus species, two Candida species, Filobasidiella neoformans, Trichosporon cutaneum, Lipomyces starkeyi, Hansenula capsulata, and one Aureobasidium pullulans strain on both compounds.
• Four strains of Aureobasidium pullulans, Candida blankii, and Cryptococcus dimennae could utilize only ascorbic acid for growth.

Conclusions:

• The majority of yeast strains tested lack the metabolic machinery to utilize ascorbic acid or iso-ascorbic acid as a sole carbon source.
• Specific yeast species, particularly within the genera Cryptococcus and Candida, possess the capability to metabolize these compounds.
• This study highlights the metabolic diversity among yeasts concerning their ability to utilize less common carbon sources.